gpio-max732x.c

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/*
 *  MAX732x I2C Port Expander with 8/16 I/O
 *
 *  Copyright (C) 2007 Marvell International Ltd.
 *  Copyright (C) 2008 Jack Ren <[email protected]>
 *  Copyright (C) 2008 Eric Miao <[email protected]>
 *
 *  Derived from drivers/gpio/pca953x.c
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; version 2 of the License.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/i2c.h>
#include <linux/i2c/max732x.h>


/*
 * Each port of MAX732x (including MAX7319) falls into one of the
 * following three types:
 *
 *   - Push Pull Output
 *   - Input
 *   - Open Drain I/O
 *
 * designated by 'O', 'I' and 'P' individually according to MAXIM's
 * datasheets. 'I' and 'P' ports are interrupt capables, some with
 * a dedicated interrupt mask.
 *
 * There are two groups of I/O ports, each group usually includes
 * up to 8 I/O ports, and is accessed by a specific I2C address:
 *
 *   - Group A : by I2C address 0b'110xxxx
 *   - Group B : by I2C address 0b'101xxxx
 *
 * where 'xxxx' is decided by the connections of pin AD2/AD0.  The
 * address used also affects the initial state of output signals.
 *
 * Within each group of ports, there are five known combinations of
 * I/O ports: 4I4O, 4P4O, 8I, 8P, 8O, see the definitions below for
 * the detailed organization of these ports. Only Goup A is interrupt
 * capable.
 *
 * GPIO numbers start from 'gpio_base + 0' to 'gpio_base + 8/16',
 * and GPIOs from GROUP_A are numbered before those from GROUP_B
 * (if there are two groups).
 *
 * NOTE: MAX7328/MAX7329 are drop-in replacements for PCF8574/a, so
 * they are not supported by this driver.
 */

#define PORT_NONE   0x0 /* '/' No Port */
#define PORT_OUTPUT 0x1 /* 'O' Push-Pull, Output Only */
#define PORT_INPUT  0x2 /* 'I' Input Only */
#define PORT_OPENDRAIN  0x3 /* 'P' Open-Drain, I/O */

#define IO_4I4O     0x5AA5  /* O7 O6 I5 I4 I3 I2 O1 O0 */
#define IO_4P4O     0x5FF5  /* O7 O6 P5 P4 P3 P2 O1 O0 */
#define IO_8I       0xAAAA  /* I7 I6 I5 I4 I3 I2 I1 I0 */
#define IO_8P       0xFFFF  /* P7 P6 P5 P4 P3 P2 P1 P0 */
#define IO_8O       0x5555  /* O7 O6 O5 O4 O3 O2 O1 O0 */

#define GROUP_A(x)  ((x) & 0xffff)  /* I2C Addr: 0b'110xxxx */
#define GROUP_B(x)  ((x) << 16) /* I2C Addr: 0b'101xxxx */

#define INT_NONE    0x0 /* No interrupt capability */
#define INT_NO_MASK 0x1 /* Has interrupts, no mask */
#define INT_INDEP_MASK  0x2 /* Has interrupts, independent mask */
#define INT_MERGED_MASK 0x3 /* Has interrupts, merged mask */

#define INT_CAPS(x) (((uint64_t)(x)) << 32)

enum {
    MAX7319,
    MAX7320,
    MAX7321,
    MAX7322,
    MAX7323,
    MAX7324,
    MAX7325,
    MAX7326,
    MAX7327,
};

static uint64_t max732x_features[] = {
    [MAX7319] = GROUP_A(IO_8I) | INT_CAPS(INT_MERGED_MASK),
    [MAX7320] = GROUP_B(IO_8O),
    [MAX7321] = GROUP_A(IO_8P) | INT_CAPS(INT_NO_MASK),
    [MAX7322] = GROUP_A(IO_4I4O) | INT_CAPS(INT_MERGED_MASK),
    [MAX7323] = GROUP_A(IO_4P4O) | INT_CAPS(INT_INDEP_MASK),
    [MAX7324] = GROUP_A(IO_8I) | GROUP_B(IO_8O) | INT_CAPS(INT_MERGED_MASK),
    [MAX7325] = GROUP_A(IO_8P) | GROUP_B(IO_8O) | INT_CAPS(INT_NO_MASK),
    [MAX7326] = GROUP_A(IO_4I4O) | GROUP_B(IO_8O) | INT_CAPS(INT_MERGED_MASK),
    [MAX7327] = GROUP_A(IO_4P4O) | GROUP_B(IO_8O) | INT_CAPS(INT_NO_MASK),
};

static const struct i2c_device_id max732x_id[] = {
    { "max7319", MAX7319 },
    { "max7320", MAX7320 },
    { "max7321", MAX7321 },
    { "max7322", MAX7322 },
    { "max7323", MAX7323 },
    { "max7324", MAX7324 },
    { "max7325", MAX7325 },
    { "max7326", MAX7326 },
    { "max7327", MAX7327 },
    { },
};
MODULE_DEVICE_TABLE(i2c, max732x_id);

struct max732x_chip {
    struct gpio_chip gpio_chip;

    struct i2c_client *client;  /* "main" client */
    struct i2c_client *client_dummy;
    struct i2c_client *client_group_a;
    struct i2c_client *client_group_b;

    unsigned int    mask_group_a;
    unsigned int    dir_input;
    unsigned int    dir_output;

    struct mutex    lock;
    uint8_t     reg_out[2];

#ifdef CONFIG_GPIO_MAX732X_IRQ
    struct mutex    irq_lock;
    int     irq_base;
    uint8_t     irq_mask;
    uint8_t     irq_mask_cur;
    uint8_t     irq_trig_raise;
    uint8_t     irq_trig_fall;
    uint8_t     irq_features;
#endif
};

static int max732x_writeb(struct max732x_chip *chip, int group_a, uint8_t val)
{
    struct i2c_client *client;
    int ret;

    client = group_a ? chip->client_group_a : chip->client_group_b;
    ret = i2c_smbus_write_byte(client, val);
    if (ret < 0) {
        dev_err(&client->dev, "failed writing\n");
        return ret;
    }

    return 0;
}

static int max732x_readb(struct max732x_chip *chip, int group_a, uint8_t *val)
{
    struct i2c_client *client;
    int ret;

    client = group_a ? chip->client_group_a : chip->client_group_b;
    ret = i2c_smbus_read_byte(client);
    if (ret < 0) {
        dev_err(&client->dev, "failed reading\n");
        return ret;
    }

    *val = (uint8_t)ret;
    return 0;
}

static inline int is_group_a(struct max732x_chip *chip, unsigned off)
{
    return (1u << off) & chip->mask_group_a;
}

static int max732x_gpio_get_value(struct gpio_chip *gc, unsigned off)
{
    struct max732x_chip *chip;
    uint8_t reg_val;
    int ret;

    chip = container_of(gc, struct max732x_chip, gpio_chip);

    ret = max732x_readb(chip, is_group_a(chip, off), &reg_val);
    if (ret < 0)
        return 0;

    return reg_val & (1u << (off & 0x7));
}

static void max732x_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
{
    struct max732x_chip *chip;
    uint8_t reg_out, mask = 1u << (off & 0x7);
    int ret;

    chip = container_of(gc, struct max732x_chip, gpio_chip);

    mutex_lock(&chip->lock);

    reg_out = (off > 7) ? chip->reg_out[1] : chip->reg_out[0];
    reg_out = (val) ? reg_out | mask : reg_out & ~mask;

    ret = max732x_writeb(chip, is_group_a(chip, off), reg_out);
    if (ret < 0)
        goto out;

    /* update the shadow register then */
    if (off > 7)
        chip->reg_out[1] = reg_out;
    else
        chip->reg_out[0] = reg_out;
out:
    mutex_unlock(&chip->lock);
}

static int max732x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
{
    struct max732x_chip *chip;
    unsigned int mask = 1u << off;

    chip = container_of(gc, struct max732x_chip, gpio_chip);

    if ((mask & chip->dir_input) == 0) {
        dev_dbg(&chip->client->dev, "%s port %d is output only\n",
            chip->client->name, off);
        return -EACCES;
    }

    /*
     * Open-drain pins must be set to high impedance (which is
     * equivalent to output-high) to be turned into an input.
     */
    if ((mask & chip->dir_output))
        max732x_gpio_set_value(gc, off, 1);

    return 0;
}

static int max732x_gpio_direction_output(struct gpio_chip *gc,
        unsigned off, int val)
{
    struct max732x_chip *chip;
    unsigned int mask = 1u << off;

    chip = container_of(gc, struct max732x_chip, gpio_chip);

    if ((mask & chip->dir_output) == 0) {
        dev_dbg(&chip->client->dev, "%s port %d is input only\n",
            chip->client->name, off);
        return -EACCES;
    }

    max732x_gpio_set_value(gc, off, val);
    return 0;
}

#ifdef CONFIG_GPIO_MAX732X_IRQ
static int max732x_writew(struct max732x_chip *chip, uint16_t val)
{
    int ret;

    val = cpu_to_le16(val);

    ret = i2c_master_send(chip->client_group_a, (char *)&val, 2);
    if (ret < 0) {
        dev_err(&chip->client_group_a->dev, "failed writing\n");
        return ret;
    }

    return 0;
}

static int max732x_readw(struct max732x_chip *chip, uint16_t *val)
{
    int ret;

    ret = i2c_master_recv(chip->client_group_a, (char *)val, 2);
    if (ret < 0) {
        dev_err(&chip->client_group_a->dev, "failed reading\n");
        return ret;
    }

    *val = le16_to_cpu(*val);
    return 0;
}

static void max732x_irq_update_mask(struct max732x_chip *chip)
{
    uint16_t msg;

    if (chip->irq_mask == chip->irq_mask_cur)
        return;

    chip->irq_mask = chip->irq_mask_cur;

    if (chip->irq_features == INT_NO_MASK)
        return;

    mutex_lock(&chip->lock);

    switch (chip->irq_features) {
    case INT_INDEP_MASK:
        msg = (chip->irq_mask << 8) | chip->reg_out[0];
        max732x_writew(chip, msg);
        break;

    case INT_MERGED_MASK:
        msg = chip->irq_mask | chip->reg_out[0];
        max732x_writeb(chip, 1, (uint8_t)msg);
        break;
    }

    mutex_unlock(&chip->lock);
}

static int max732x_gpio_to_irq(struct gpio_chip *gc, unsigned off)
{
    struct max732x_chip *chip;

    chip = container_of(gc, struct max732x_chip, gpio_chip);
    return chip->irq_base + off;
}

static void max732x_irq_mask(struct irq_data *d)
{
    struct max732x_chip *chip = irq_data_get_irq_chip_data(d);

    chip->irq_mask_cur &= ~(1 << (d->irq - chip->irq_base));
}

static void max732x_irq_unmask(struct irq_data *d)
{
    struct max732x_chip *chip = irq_data_get_irq_chip_data(d);

    chip->irq_mask_cur |= 1 << (d->irq - chip->irq_base);
}

static void max732x_irq_bus_lock(struct irq_data *d)
{
    struct max732x_chip *chip = irq_data_get_irq_chip_data(d);

    mutex_lock(&chip->irq_lock);
    chip->irq_mask_cur = chip->irq_mask;
}

static void max732x_irq_bus_sync_unlock(struct irq_data *d)
{
    struct max732x_chip *chip = irq_data_get_irq_chip_data(d);

    max732x_irq_update_mask(chip);
    mutex_unlock(&chip->irq_lock);
}

static int max732x_irq_set_type(struct irq_data *d, unsigned int type)
{
    struct max732x_chip *chip = irq_data_get_irq_chip_data(d);
    uint16_t off = d->irq - chip->irq_base;
    uint16_t mask = 1 << off;

    if (!(mask & chip->dir_input)) {
        dev_dbg(&chip->client->dev, "%s port %d is output only\n",
            chip->client->name, off);
        return -EACCES;
    }

    if (!(type & IRQ_TYPE_EDGE_BOTH)) {
        dev_err(&chip->client->dev, "irq %d: unsupported type %d\n",
            d->irq, type);
        return -EINVAL;
    }

    if (type & IRQ_TYPE_EDGE_FALLING)
        chip->irq_trig_fall |= mask;
    else
        chip->irq_trig_fall &= ~mask;

    if (type & IRQ_TYPE_EDGE_RISING)
        chip->irq_trig_raise |= mask;
    else
        chip->irq_trig_raise &= ~mask;

    return max732x_gpio_direction_input(&chip->gpio_chip, off);
}

static struct irq_chip max732x_irq_chip = {
    .name           = "max732x",
    .irq_mask       = max732x_irq_mask,
    .irq_unmask     = max732x_irq_unmask,
    .irq_bus_lock       = max732x_irq_bus_lock,
    .irq_bus_sync_unlock    = max732x_irq_bus_sync_unlock,
    .irq_set_type       = max732x_irq_set_type,
};

static uint8_t max732x_irq_pending(struct max732x_chip *chip)
{
    uint8_t cur_stat;
    uint8_t old_stat;
    uint8_t trigger;
    uint8_t pending;
    uint16_t status;
    int ret;

    ret = max732x_readw(chip, &status);
    if (ret)
        return 0;

    trigger = status >> 8;
    trigger &= chip->irq_mask;

    if (!trigger)
        return 0;

    cur_stat = status & 0xFF;
    cur_stat &= chip->irq_mask;

    old_stat = cur_stat ^ trigger;

    pending = (old_stat & chip->irq_trig_fall) |
          (cur_stat & chip->irq_trig_raise);
    pending &= trigger;

    return pending;
}

static irqreturn_t max732x_irq_handler(int irq, void *devid)
{
    struct max732x_chip *chip = devid;
    uint8_t pending;
    uint8_t level;

    pending = max732x_irq_pending(chip);

    if (!pending)
        return IRQ_HANDLED;

    do {
        level = __ffs(pending);
        handle_nested_irq(level + chip->irq_base);

        pending &= ~(1 << level);
    } while (pending);

    return IRQ_HANDLED;
}

static int max732x_irq_setup(struct max732x_chip *chip,
                 const struct i2c_device_id *id)
{
    struct i2c_client *client = chip->client;
    struct max732x_platform_data *pdata = client->dev.platform_data;
    int has_irq = max732x_features[id->driver_data] >> 32;
    int ret;

    if (pdata->irq_base && has_irq != INT_NONE) {
        int lvl;

        chip->irq_base = pdata->irq_base;
        chip->irq_features = has_irq;
        mutex_init(&chip->irq_lock);

        for (lvl = 0; lvl < chip->gpio_chip.ngpio; lvl++) {
            int irq = lvl + chip->irq_base;

            if (!(chip->dir_input & (1 << lvl)))
                continue;

            irq_set_chip_data(irq, chip);
            irq_set_chip_and_handler(irq, &max732x_irq_chip,
                         handle_edge_irq);
            irq_set_nested_thread(irq, 1);
#ifdef CONFIG_ARM
            set_irq_flags(irq, IRQF_VALID);
#else
            irq_set_noprobe(irq);
#endif
        }

        ret = request_threaded_irq(client->irq,
                       NULL,
                       max732x_irq_handler,
                       IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
                       dev_name(&client->dev), chip);
        if (ret) {
            dev_err(&client->dev, "failed to request irq %d\n",
                client->irq);
            goto out_failed;
        }

        chip->gpio_chip.to_irq = max732x_gpio_to_irq;
    }

    return 0;

out_failed:
    chip->irq_base = 0;
    return ret;
}

static void max732x_irq_teardown(struct max732x_chip *chip)
{
    if (chip->irq_base)
        free_irq(chip->client->irq, chip);
}
#else /* CONFIG_GPIO_MAX732X_IRQ */
static int max732x_irq_setup(struct max732x_chip *chip,
                 const struct i2c_device_id *id)
{
    struct i2c_client *client = chip->client;
    struct max732x_platform_data *pdata = client->dev.platform_data;
    int has_irq = max732x_features[id->driver_data] >> 32;

    if (pdata->irq_base && has_irq != INT_NONE)
        dev_warn(&client->dev, "interrupt support not compiled in\n");

    return 0;
}

static void max732x_irq_teardown(struct max732x_chip *chip)
{
}
#endif

static int __devinit max732x_setup_gpio(struct max732x_chip *chip,
                    const struct i2c_device_id *id,
                    unsigned gpio_start)
{
    struct gpio_chip *gc = &chip->gpio_chip;
    uint32_t id_data = (uint32_t)max732x_features[id->driver_data];
    int i, port = 0;

    for (i = 0; i < 16; i++, id_data >>= 2) {
        unsigned int mask = 1 << port;

        switch (id_data & 0x3) {
        case PORT_OUTPUT:
            chip->dir_output |= mask;
            break;
        case PORT_INPUT:
            chip->dir_input |= mask;
            break;
        case PORT_OPENDRAIN:
            chip->dir_output |= mask;
            chip->dir_input |= mask;
            break;
        default:
            continue;
        }

        if (i < 8)
            chip->mask_group_a |= mask;
        port++;
    }

    if (chip->dir_input)
        gc->direction_input = max732x_gpio_direction_input;
    if (chip->dir_output) {
        gc->direction_output = max732x_gpio_direction_output;
        gc->set = max732x_gpio_set_value;
    }
    gc->get = max732x_gpio_get_value;
    gc->can_sleep = 1;

    gc->base = gpio_start;
    gc->ngpio = port;
    gc->label = chip->client->name;
    gc->owner = THIS_MODULE;

    return port;
}

static int __devinit max732x_probe(struct i2c_client *client,
                   const struct i2c_device_id *id)
{
    struct max732x_platform_data *pdata;
    struct max732x_chip *chip;
    struct i2c_client *c;
    uint16_t addr_a, addr_b;
    int ret, nr_port;

    pdata = client->dev.platform_data;
    if (pdata == NULL) {
        dev_dbg(&client->dev, "no platform data\n");
        return -EINVAL;
    }

    chip = kzalloc(sizeof(struct max732x_chip), GFP_KERNEL);
    if (chip == NULL)
        return -ENOMEM;
    chip->client = client;

    nr_port = max732x_setup_gpio(chip, id, pdata->gpio_base);

    addr_a = (client->addr & 0x0f) | 0x60;
    addr_b = (client->addr & 0x0f) | 0x50;

    switch (client->addr & 0x70) {
    case 0x60:
        chip->client_group_a = client;
        if (nr_port > 8) {
            c = i2c_new_dummy(client->adapter, addr_b);
            chip->client_group_b = chip->client_dummy = c;
        }
        break;
    case 0x50:
        chip->client_group_b = client;
        if (nr_port > 8) {
            c = i2c_new_dummy(client->adapter, addr_a);
            chip->client_group_a = chip->client_dummy = c;
        }
        break;
    default:
        dev_err(&client->dev, "invalid I2C address specified %02x\n",
                client->addr);
        ret = -EINVAL;
        goto out_failed;
    }

    mutex_init(&chip->lock);

    max732x_readb(chip, is_group_a(chip, 0), &chip->reg_out[0]);
    if (nr_port > 8)
        max732x_readb(chip, is_group_a(chip, 8), &chip->reg_out[1]);

    ret = max732x_irq_setup(chip, id);
    if (ret)
        goto out_failed;

    ret = gpiochip_add(&chip->gpio_chip);
    if (ret)
        goto out_failed;

    if (pdata->setup) {
        ret = pdata->setup(client, chip->gpio_chip.base,
                chip->gpio_chip.ngpio, pdata->context);
        if (ret < 0)
            dev_warn(&client->dev, "setup failed, %d\n", ret);
    }

    i2c_set_clientdata(client, chip);
    return 0;

out_failed:
    max732x_irq_teardown(chip);
    kfree(chip);
    return ret;
}

static int __devexit max732x_remove(struct i2c_client *client)
{
    struct max732x_platform_data *pdata = client->dev.platform_data;
    struct max732x_chip *chip = i2c_get_clientdata(client);
    int ret;

    if (pdata->teardown) {
        ret = pdata->teardown(client, chip->gpio_chip.base,
                chip->gpio_chip.ngpio, pdata->context);
        if (ret < 0) {
            dev_err(&client->dev, "%s failed, %d\n",
                    "teardown", ret);
            return ret;
        }
    }

    ret = gpiochip_remove(&chip->gpio_chip);
    if (ret) {
        dev_err(&client->dev, "%s failed, %d\n",
                "gpiochip_remove()", ret);
        return ret;
    }

    max732x_irq_teardown(chip);

    /* unregister any dummy i2c_client */
    if (chip->client_dummy)
        i2c_unregister_device(chip->client_dummy);

    kfree(chip);
    return 0;
}

static struct i2c_driver max732x_driver = {
    .driver = {
        .name   = "max732x",
        .owner  = THIS_MODULE,
    },
    .probe      = max732x_probe,
    .remove     = __devexit_p(max732x_remove),
    .id_table   = max732x_id,
};

static int __init max732x_init(void)
{
    return i2c_add_driver(&max732x_driver);
}
/* register after i2c postcore initcall and before
 * subsys initcalls that may rely on these GPIOs
 */
subsys_initcall(max732x_init);

static void __exit max732x_exit(void)
{
    i2c_del_driver(&max732x_driver);
}
module_exit(max732x_exit);

MODULE_AUTHOR("Eric Miao <[email protected]>");
MODULE_DESCRIPTION("GPIO expander driver for MAX732X");
MODULE_LICENSE("GPL");